Any Hatz mechanics???

Ok, when it rains it pours..... I've got a 4L40C silent pac on my service truck as a power unit for a hydraulic pump, to power my air compressor and crane.


LONG story short...First fuel solenoid decides to crap out (((boom up, and outriggers down...got it all got taken care of and I got home)))...Started looking, part number good, part on BO, not available until ??????? So, I did work around with a complete miniture solenoid valve and it worked great.

Got it going and ran it several times for a few hours over the past week, and it ran great. I ran it several times Monday but when I went to start it for about the 4th time the starter wouldn't turn over. Left me up the creek again job wise, but fortunately the starter wasn't bad, just the solenoid...Still I had it gone through anyway since it hadn't been touched in 10 years. Got it all back together and cranked it over to make sure it worked, which it did, but didn't start it because it was late when I got it all back together.

Fast forward to Wednesday morning and I went to start it again. It would turn over great, but would not start at all. A bit of investigation revealed it was building absolutely no oil pressure to move the rack and turn the fuel on.

Now, these engines won't run without oil pressure so I know it had oil pressure on Monday when I was running it wide open using the compressor, just before the starter died. It then did nothing but set until I got the starter rebuilt so it shouldn't have been able to 'break' just sitting there. Now it turn over great but will build absolutely no oil pressure. I watched the guy rebuild my starter, and even caled to insure nothing he did could have made it turn backwards (stupid mistake/problem I know, but I have seen it happen), but this startwr would require parts not replaced to make it turn the other way.

Now the oil line going to the solenoid valve is dead, no flow, and I can remove the oil filter, which is supposed to be the first item past the pump, and again no flow there either when turning it over.

Funny thing, the pump is gear driven, and the front pulley drives off of it. The pulley is turning so I know the pump has to be moving.....but, again, no flow/pressure. Even worn out, a positive displacement gear pump should be moving some oil when it turns, even if it won't build much pressure, but this thing has no flow at all.

In the end what's happening 'can't' happen...but it is happening. Have any of ya'll ever worked on one, or seen anything like this happen before? I talked to one hatz service guy and he said the same thing I do, it can't happen like it is. Yes, major internal damage could cause problems, but there is no indication of anything having happened when I shut it down on Monday, not in the time since........So, any ideas,or suggestions would be greatly appreciated.

And yes, I am thinking seriously about trashing the Hatz for a V465 Wisconsin. I can buy a good, used/surplus, complete, running motor for just a bit more, and in some cases less, than the cost of a replacement oil pump (More than $1300 the cheapest I have found)......

Stuck open pressure regulator In/on/for the pump. If stuck open even a little it will not build enough pressure to flow more than the leak. (guess) Jim

I have seen Onan pumps break off at the Shaft. Gear still turns ok,but the pump rotors don't move. Also have seen relief valves stick open. How hard is it to get to the pump.

I'm not a Hatz expert - do have a small single cylinder model, if it cranks slow it will never deliver fuel - get up to a certain speed and it takes off. Is it possible that you have a weak ground / battery / etc... and the cranking speed is down?

Thought about that myself until I looked at a service book that shows the oil flow through the engine. Unfortunately the filter is the FIRST thing the oil goes through when leaving the pump...When I pull the filter off and turn it over, there is absoultely no oil flowing at all. Unless the pump was completely unhooked from the geartrain it should move some oil, even if it wasn;t under full pressure, but nothing...and the pump is turning because the drive pully for the fan is driven directly through the pump and it is turning, which means the pump has to be turning.

New starter, and three truck sized batteries behind it when I flip a switch to tie the two off the truck into the system, so no problems there. As far as the starting slow this one has to build oil pressure to push a piston that allows the fuel rack to 'turn the fuel on', and it's not building pressure at all. The solenoid valve I installed when the factory one went is working properly, is what allows oil to get to the piston, and it's working properly. The problem is no oil is getting up to it....or through the filter which is the first place the oil goes when it leaves the pump.

Most of the front of the engine has to come off to get to it. The fact it's a Silent Pac and incapsulated makes it even worse. That said the belt that drives the fan is driven off a pulley that is connected to a shaft coming off the input shaft to the oil pump. The fact that the pulley is turning tells me the oil pump is also turning. The problem is how can a gear pump turn and move absolutely no oil. Granted I could see it being worn and not building the necessary pressure to make things work, but absolutely no flow from a turning pump "can't happen" but it is.....

(quoted from post at 17:25:48 09/19/13) Most of the front of the engine has to come off to get to it. The fact it's a Silent Pac and incapsulated makes it even worse. That said the belt that drives the fan is driven off a pulley that is connected to a shaft coming off the input shaft to the oil pump. The fact that the pulley is turning tells me the oil pump is also turning. The problem is how can a gear pump turn and move absolutely no oil. Granted I could see it being worn and not building the necessary pressure to make things work, but absolutely no flow from a turning pump "can't happen" but it is.....

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Provided the engine has oil in it.

Or the gears in the pump sheared the key on the shaft. (guessing) Jim

I had a oil pump split the gears when I changed the oil once was running fine with pressure shut it off dumped the oil and changed the oil and filter started it up no oil pressure. you say the pulley is turning but is it on the other end of the driven shaft of the oil pump? and the other shaft would be like an idler shaft that the other pump gear spins on? hope that makes sense

Based on what I can tell from the service andparts books the pulley is attached to the oil pumps driven shaft...that's why what's happening makes no sense.

Kinda got that feeling myself, but the guy at the dealership said he had NEVER seen anything like this happen. Unfortunately I tend to run into the 'never happens...strange crap' so the whole problem being nothing more than a key makes about as much, if not more, sense than anything else I have thought of and deemed impossible....

Wayne, even though it "never happens", you know the old saying too, "There's always gotta be a first time." I have never worked on a Hatz, but I have read some service material on a small one, which made me NOT want to work on one anyway.

How is the pump gear (or rotor?) attached to the shaft? If it is a shrink fit the shaft can spin free if the gear splits.

Not at all familiar with your engine, but can you get to the oil pick tube easily ? could you take a rubber tip blow gun and blow up thru the pickup to the pump, or even just try blowing back thru the oil filer passage to the pump ? Nothing to lose blowing back thru the filter, might free up a stuck regulator; just a guess , something easy to try maybe. Mark